Function hiding in C occurs when a derived class defines a function with the same name as a base class function, making the base version inaccessible through the derived class. This happens when the base function isn’t virtual or signatures don’t match for overriding, and no using declaration is used. 1. It blocks all overloads of the base function. 2. Name lookup stops at the derived class. 3. Fix it using using Base::func, explicit calls, or renaming. 4. Useful when intentionally restricting access but often unintended and should be managed carefully.
Function hiding in C is when a function in a derived class prevents the base class version of the same function from being accessible through the derived class. This usually happens when you have a function with the same name (but possibly different parameters or return type) in both the base and derived classes.

It’s important to note that this behavior is different from function overriding, which only applies to virtual functions and maintains a connection between the base and derived versions. Function hiding completely hides the base class's function when accessed via the derived class.

How Does Function Hiding Happen?
Function hiding occurs in C under these conditions:
- You define a function in a derived class with the same name as a function in the base class.
- The function in the base class is not declared virtual, or even if it is, but the signatures don't match exactly for override.
- The derived class does not explicitly use
using BaseClass::functionName;
to bring the base version into scope.
For example:

class Base { public: void show() { cout << "Base show"; } }; class Derived : public Base { public: void show(int x) { cout << "Derived show with int"; } };
Now, if you try to call show()
without an argument on a Derived
object, it won’t find the base version — it's hidden.
Why Does It Happen?
C uses a rule called name lookup: when you call a function like obj.show()
, the compiler starts looking at the class of obj
and stops as soon as it finds any function named show
. If Derived
has a show
, it doesn’t bother checking Base
.
This means even if the parameter lists are different, once you declare a function with the same name in the derived class, all base class overloads are hidden.
How to Fix or Avoid It
If you want to keep access to both versions of the function, there are a couple of options:
Use the
using
declaration in the derived class:class Derived : public Base { public: using Base::show; // brings Base's show into scope void show(int x) { cout << "Derived show with int"; } };
Now calling
obj.show()
will work again, andobj.show(5)
will call the derived version.Alternatively, call the base class function explicitly:
Derived d; d.Base::show(); // calls Base's show
Or rename one of the functions to avoid conflict if hiding was unintentional.
- You're designing a derived class and intentionally want to remove access to certain inherited functions.
- You’re replacing functionality entirely and don’t want old versions to be used accidentally.
When Is It Useful?
Function hiding isn't always a bug — sometimes it's intentional. For example:
But in most cases, especially when working with inheritance hierarchies and expecting polymorphic behavior, it's better to use virtual
functions and proper overriding instead of relying on function hiding.
So, function hiding is basically a side effect of how name resolution works in C . It can trip you up if you're not aware, but with using
declarations or careful naming, you can manage it.
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